Your Document Number is the 8 or 10-digit number on the lower right corner of your license, permit or non-driver ID, or on the back if it was produced after January 28, 2014.
Driver License, Learner Permit & Non-Driver ID (Over 21)
Driver License, Learner Permit & Non-driver ID (Under 21)
Enhanced Driver License, Learner Permit & Non-Driver ID (EDL)
On enhanced documents issued after 1/28/2014, the document number begins after 'IDUSA' and is on the back of the document.